1. AST 473 Cessna Citation II- CE-550 Systems
Dr. Barnhart
Ice & Rain System

2. Anti-Ice, De-Ice, and Rain Protection Systems
Anti-Ice Systems:
Wing
Engine Components
Windshield (bleed air and isopropyl alcohol)
Pitot-Static/AOA systems
*All components should be activated prior to entering icing conditions

3. De-Icing Systems
Pneumatic boots on outboard wing sections, horizontal and vertical tail segments.
*Activated upon ice accumulation

4. Rain Protection
Compressor bleed air directed through louvers provides a layer of air directing rain off of the windscreen.

5. Anti-Ice General Detail
Engine Anti-Ice Protection:
T(1) Temp. probe (bleed air)
Nose Cone (bleed air)
Nacelle Inlet (bleed air)
1st set of engine stator vanes (bleed air)
Inboard Wing sections (electric)
Nose cone and T(1) probe are continually protected while the others require the engine anti-ice switch to be positioned on

6. Pitot/Static Anti-Ice
Pilot switch controls DC power to two pitot masts, four static ports, and the AOA probe (breakers located on pilot’s panel)
P/S HTR OFF annunciator illuminates anytime power is disrupted to this circuit (switch off or failure- AOA heater not on this warning circuit)
*Ground operation to P/S Heat limited to two minutes to prevent AOA probe damage.

7. Windshield Anti-Ice and Rain Removal
Anti-Ice protection controlled via a three-way switch (hi, low, and off) on pilot’s panel, which, along with the two bleed air valve control knobs direct bleed air to the windshield
Main power switch de-energizes the windshield bleed-air valve open and activates a temp. controller

8. Windshield Anti-ice
HI position /- 5 deg.- use when OAT is At or below -18 deg. C , Low 127 +/-5 deg.- use when OAT is above -18 deg. C
Temp. is maintained by the temp. controller which receives 3 inputs:
W/S Bleed switch position
2 ea. Temp. sensor inputs
*Sensor modifies amt. of ram air passing through the heat exchanger

9. Windshield Anti-ice
Modified Bleed air then passes through a series of nozzles onto the windscreen
Additional temp. sensor located in the bleed air duct- automatically energizes closed the electric bleed air solenoid valve if bleed air temp. > 146 deg. C.
At this point the W/S Air O’HEAT annunciator illuminates (happens at high power/low airspeed config.- valve resets and light extinguishes automatically upon correction

10. Windshield Anti-ice
If the W/S AIR O’HEAT light illuminates with the switch OFF:
Bleed-air valve opened pressurizing the duct- sensed by a duct pressure switch
Pilot action: ensure W/S Bleed Valves OFF
NOT an over pressure but a valve position warning

11. Windshield Anti-ice
In DC failure: Bleed air Solenoid valve opens- W/S bleed air avail. But no O’Heat warning and temp cnt’l are inop.
Operation of system is verified by the noise when valves are open thus damage should be prevented in a DC pwr. failure

12. Windshield Alcohol Back up to W/S Bleed system Components:
Reservoir- 2 qts. Capacity isopropyl alcohol
Switch- W/S ALCOHOL- 2 pos.
Pump
Nozzles
*Up to 10 min. protection- pilot’s side only- fluid qty. verified on pre-flight via a sight gauge in rt. Hand nose cmpt.

13. Rain Removal System
Uses Bleed air from Windshield De-ice system via doors
Activated by pulling open the PULL RAIN handle under W/S Bleed Air knobs
Rotate W/S Bleed air knobs to MAX
Position W/S Bleed switch to LOW
During low power settings (landing) rotate co-pilot’s W/S Bleed Air knob to OFF
RAIN handle hard to pull of bleed air already on

14. Engine Anti-Ice
Meant as an ice preventative measure- activation after ice accumulation can cause engine damage
Activate when OAT is between +10 and -30 deg. C
For sustained Ground operation in visible moisture at the above temps. Activate engine anti-ice for 1 min. out of 4 AOA 65%N(2).

15. Engine Anti-Ice Components:
Electric Heating elements in inboard scn. Of each wing leading edge
Bleed air heated engine nacelle inlets
First row of stationary stators behind the first state fan and prior to the booster stage
Nose Cone and T(1) probe continually on
Activated by ENGINE ANTI-ICE switch on pilot’s panel

16. Engine Anti-Ice Operation
Select ENGINE ANTI-ICE ON:
If engines above 60% for > 5 sec. (throttle micro-switch) 2 bleed-air solenoid valves de-energize open allowing bleed air to flow to nacelle inlet and stator vanes
Look for a Rise in ITT and a slight drop in RPM
5 sec. time delay built in to aid in faster engine spool up during periods of high demand (ie. Go-around)

17. Engine Anti-Ice Operation
ENG ANTI-ICE LH/RH annunciators illuminate when switches placed on and extinguish when nacelle inlet temps. >224 deg. F AND Stator vane bleed-air solenoid valve open, AND wing leading edge heaters are operating w/ temp AOA 60 deg. F

18. Engine Anti-Ice
Annunciator will re-illuminate for any of the following:
Stator valve fails to open (5s delay normal)
Nacelle leading edge temp < 104 deg. C
Inboard wing scn. Temp < 16 deg. C
Failure of 1 or > wing heat elements (Light will illuminate each cycle if one failed)
Failure of the temp. controller (light cycles off when the leading edges are heated and on when temp. limit is reached).

19. Engine Anti-Ice Caution
During descents in icing conditions avoid throttle settings below 60% as engine bleed-air solenoid valves will close (annunciator will illuminate)

20. Wing Anti-Ice System
5 elec. Heating elements in each wing each with it’s own CB and current sensor powered by main DC buses respectively
Operated when power is on regardless of throttle position.
Maintains skin temp. bet. 54 and 78 C
Over-temp sensor on upper surface (cooler) activates at 75 C and opens circuit maintaining 69 C.- Activates ENG ANTI-ICE LH/RH

21. Wing Anti-Ice System
Operation monitored by illumination of green lights above each ignition switch, illumination of the ENG ANTI-ICE LH/RH annunciator and a 150 amp rise on each ammeter.
If throttles are above 60% N(2)
During Electrical Failure both nacelle inlet valve and stator vane valve will fail open and engine will be anti-iced continuously

22. De-Ice System
Boots on outer wing leading edges, and horizontal and vert. stabilizer
Controlled by SURFACE DE-ICE Switch on pilot’s instrument panel
Bleed air is available to system when engines operating- timer switch controls automatic sequencing of boot operation
Power is via SURFACE DE-ICE CB

23. De-Ice System Overview
Activate when ¼ to ½ inch of ice present
Use ½ inch thick stall strip on wing leading edge as a guide- early activation may cause bridging- (use L. wing inspn. Light)
Ice thicker than ½ inch may not be able to be removed by boots
If DC fails- avoid icing conditions
Avoid activation below -40Deg. C- boot damage may occur

24. De-Ice System Operation
SURFACE DE-ICE switch- de-energized to OFF- all 3 control valves de-energized
In OFF the 3 valves are dumping bleed air overboard via venturis that create vacuum to hold boots deflated
To cycle boots momentarily place switch in SURFACE DE-ICE Position- energized system timer for 2 ea.6 sec. cycles- 1st cycle is empennage (wings held tight)

25. De-Ice System Operation
2nd cycle- wings (empennage held tight)
After 12 seconds (2 ea. 6 sec. cycles) all 3 valves are de-energized closed and vacuum is applied to all boots to hold closed
During operation (as each set is inflated) the white SURF DEICE annunciator is illuminated by a pressure switch
In the event of a malfunction and boots remain inflated- cycle switch to RESET- overrides the system timer and de-energizes all control valves- holds boots deflated.

26. The End